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title: 'Reading Potter Stewart on recognition'
layout: post
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In a famous [US Supreme Court case on pornography](https://en.wikipedia.org/wiki/Jacobellis_v._Ohio): "I shall not today attempt further to define the kinds of material I understand to be embraced within that shorthand description, and perhaps I could never succeed in intelligibly doing so. But I know it when I see it and the motion picture involved in this case is not that."
Some friends/colleagues have been reading this as: "Stewart is not arguing that he can recognise something, in his case pornography, but that he can be confident of its absence". This is kind of important in legal and boundary-object terms.
But I'm not sure that's right.
He actually says, explicitly, the opposite: "I know it when I see it" and not: "I don't know it when I see it but this is not it" (those two statements are not interchangeable). This is not hypothetical; he says, outright, that he knows it when it is presented to his sight. He has a self-understood category ("the kinds of material that I understand to be embraced within that shorthand description"), pornography, that he can recognize ("I know it") when it is presented ("when I see it") and can compare motion pictures put before him ("the motion picture involved in his case") with this taxonomy for classification. It is Potter's exact words that if the motion picture _were_ pornographic, he could have made that call too, it just so happens that the one here today for his court case "is not".
What he says is that he will not, right here in this case, and possibly cannot universally, codify in formal legal language a set of principles that define his understanding of pornography: "I shall not today attempt further to define the kinds of material I understand to be embraced within that shorthand description, and perhaps I could never succeed in intelligibly doing so." That said, there are already some definitions present here, since he says that he will not attempt "_further_" to define the term.
What I think we can actually draw from this is:
1. Potter Stewart claims to be able to recognize pornography when it is present.
2. Potter Stewart claims that he can recognize work that is not pornographic in the actions of his ruling.
3. Potter Stewart will not attempt to further formally clarify his definition of pornography (which makes it legally hard to argue against; like some kind of private legal knowledge).
4. Potter Stewart believes it may not be possible to actually publicly and comprehensively define pornography.
In other words, Potter Stewart uses an anti-foundationalist and private definition of pornography to make category judgements. He legitimates this through an _a posteriori_ claim of experience; that he can know it when it is seen.